Metabolism of flavoneC-glucosides andp-coumaric acid from antioxidant of bamboo leaves (AOB) in rats

Abstract

The metabolism of flavoneC-glucosides andp-coumaric acid from antioxidant of bamboo leaves (AOB) in rats is discussed systematically in the present study. Following single oral administration of AOB,p-coumaric acid was detected in plasma but not in gastrointestinal tract extracts and faeces, and the corresponding absorption pharmacokinetic curve at different time points showed a prolonged elimination phase withp-coumaric acid being detected in the kidneys and excreted as its original form (1·80 (sd0·24) % and 1·90 (sd0·26) % at 12 and 24 h, respectively). However, the four flavoneC-glucosides orientin, homoorientin, vitexin and isovitexin were poorly absorbed in the gastrointestinal tract. More than 50 % recovery of flavoneC-glucosides was determined at 12 h and faeces containing these four analytes (21·23 (sd1·92) %) were excreted at 24 h. These data suggested that the effective time these compounds were in the colon was long enough so that they could exert their antioxidant activity and scavenge free radicals. Besides the excretion of the original forms, moieties of the flavoneC-glucosides were hydrolysed by deglycosylation and the opening of the heterocyclic C ring. Some small molecules such as phloroglucinol (PG), hydrocaffeic acid (HCA) and phloretic acid (PA) were detected and identified as metabolites of the flavoneC-glucosides. In the present work, we compared the metabolic fate of flavoneC-glucosides to that of flavoneO-glucosides in rats, and evaluated the absorption, tissue distribution and excretion of flavoneC-glucosides in AOB on their metabolism for the first time.